Factors inducing mushiness in stored prawns

Abstract

After 1 week of storage on ice, little change was observed between the SDS-PAGE patterns of myofibrillar proteins extracted from fresh prawns with firm texture and mushy prawns. Trypsin and hepatopancreas homogenate incubated at 0°C with prawn segments, can cause mushiness at a very low level of added proteolytic activity. Chymotrypsin added at comparable amounts of activity does not cause mushiness, although fragmentation of high molecular weight components of myofibrillar proteins was demonstrated. Collagenase induces mushiness when assisted by low amounts of proteolytic activity. Purified collagenase, devoid of measurable amounts of proteolytic activity, did not cause mushiness but imparted a soft texture. Mushiness in prawns stored on ice is not caused by an endogenous proteolytic system in the muscle. The main cause of mushiness following ice storage, appears to be due to diffusion of proteolytic and collagenolytic enzymes from the autolyzing hepatopancreas.